Abstract
We conducted a two-dimensional numerical model to analyze the generation of tectonic over-pressure, which is a positive deviation from lithostatic pressure, for deep slabs which are anchored at the 660 km phase boundary. The formation of the ductile shear zone under a compressional tectonic setting induces tectonic over-pressure. We first propose that an apparent shear zone originated from an elastic heterogeneity in the phase loop, which is the two-phase (i.e., olivine and wadsleyite) coexistence interval around the 410 km boundary within subducting oceanic lithospheres, can cause tectonic over-pressure with a range from 0.3 to 1.5 GPa. This over-pressure significantly impacts the formation of the olivine-wadsleyite phase transition. The flattening of the olivine-wadsleyite interface by over-pressure is well-resolved. Therefore, we argue that the over-pressure should be applied when analyzing the phase boundary within the subducting lithosphere. Our results provide a new insight on the interplay among the phase transition, shear zone formation and tectonic over-pressure.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 59-69 |
| Number of pages | 11 |
| Journal | Earth and Planetary Science Letters |
| Volume | 413 |
| DOIs | |
| State | Published - Mar 1 2015 |
Bibliographical note
Funding Information:We thank to two anonymous reviewers for their careful reviews, which significantly improved our manuscript. This research was supported by the National Research Foundation of Korea ( NRF-2014R1A6A3A04055841 ) for B.-D. So and U.S. National Science Foundation grants in the Collaboration of Mathematics and Geosciences (CMG) program and Geochemistry for D.A. Yuen. We also thank discussions with Yuri Podladchikhov.
Publisher Copyright:
© 2015 The Authors.
Keywords
- Olivine-spinel coexistence zone
- Phase loop
- Phase transition
- Shear heating
- Subducting slab
- Tectonic over-pressure